second:The dates on my outputall the text file on the Sd card are dated 1/1/2000[img][file:///C:/Users/nerito/Pictures/arduino.jpg/img]

Your Arduino has no idea what the date is and I guess the 1/1/2000 is just windows putting a name to nothing.Your best bet is to get a real time clock and use that to name your files according to date and time. I record the time in the data and just use the date for the filename - 20130218.csv

Today I got one of these - https://www.adafruit.com/index.php?main_page=adasearch&q=ads1115 - not tested, not even read the datasheet, but it is capable of a few 100 samples @16 bit per second. at 16 bits I expect low(er) noise